1. Field of the Invention
The present invention relates to a portable semiconductor device and a method of manufacturing the same. More particularly, the present invention relates to a portable semiconductor device in which functional parts of the thin semiconductor device, such as an IC card or a non-contact IC card, are embedded in a foamed resin and protected by a resin or the like, and a method of manufacturing such a portable semiconductor device.
2. Description of the Related Art
Portable semiconductor devices (hereinafter referred to as IC cards) in which electronic parts thereof are embedded in a card body in order to eliminate space in the body are known. FIG. 20 illustrates the manufacturing method of a non-contact IC card having the above-described configuration, disclosed in Japanese Patent Laid-Open No. 1-241496. To manufacture an IC card 1 shown in FIG. 20, first a module 6, in which an IC 3 and an electric cell 4 are mounted on a circuit board 2, is accommodated in a casing 7. Next, a thermosetting resin 11 is injected into the casing 7 from a hole 7C formed in an upper casing portion and then set by heating the resin in such a manner that there is no space left in the casing 7 so as to fix the casing 7 and the module 6 as one unit.
In another conventional manufacturing method shown in FIG. 21, the module 6 is sandwiched by casing portions 7D and 7E, and then the two casing portions 7D and 7E are adhered to each other to form the IC card 1. The casing is made up of the upper and lower casing portions 7D and 7E. The inner surface of the upper casing portion 7D has recessed portions 7Da corresponding to the irregularities of the parts mounted in the module 6. To complete the IC card 1, the module 6 is fitted into the upper casing portion 7D, and then the lower casing portion 7E is adhered to the upper casing portion 7D to cover the module 6.
Since the IC cards 1 shown are of the portable type, if there is a space within the IC card 1, the IC card 1 may readily break. This drawback may be eliminated by increasing the thickness of the casing 7. However, this makes it inconvenient for the card to be carried from one place to another. Further, if there is a space in the IC card 1, the surface of the IC card 1 may partially recede inwardly when the design is printed on the surface of the IC card 1. The configuration of the IC cards 1 shown in FIGS. 20 and 21 ensures an increases in the strength of the IC card 1, and eliminates the drawbacks generated during printing.
However, in the method in which the resin is injected into the casing from part thereof to fill in the space in the casing after the module is accommodated in the casing, the resin is injected into the casing under a vacuum so that the casing can be completely filled with the resin. However, the degree to which the injected resin is excessive or short or the degree to which the injected resin shrinks due to setting, partially differs depending on the presence or absence of the built-in parts, resulting in undulation of the surface of the IC card and making the provision of a flat and uniform surface difficult. In addition, the injected resin may soil the outer surface of the IC card.
Where the module is accommodated in the casing having irregularities corresponding to the module, the casing which can engage with the built-in module is required. This in turn requires the same number of molds as that of card types. In this case, partial alteration in the parts mounted on the circuit board requires alteration of the mold.